Effect of Doping Fluorine in Offset Region on Performance of Coplanar a-IGZO TFTs

We report the effect of doping fluorine in the offset region on the performance of coplanar amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). The TFTs with 4-μm offset length at both sides of the gate were fabricated. Hall mobility of the offset region a-IGZO increases, and its resistivity (ρ) decreases with increasing F doping concentration. The TFTs with 7 × 10
¹⁹
cm
^-3
carrier concentration in the offset region exhibit the field-effect mobility of 27.17 cm
²
/V· s. The fabricated 23-stage ring oscillator (RO) shows an oscillation frequency of 2.27 MHz at the supply voltage of 20 V with a propagation delay of 9.5 ns/stage, which